Peiying Liu Wang1, Jinsoo Uh1, Hanzhang Lu1
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States
Although ASL has been widely used for measurement of CBF, we do not know which compartment the labeled spins are located at the time of detection. Here we used the T2 value of the labeled spins to probe whether the detected ASL signal is located in artery, tissue or even vein. Our data suggest that, at typical delay time of 1.5 seconds, most of the detected spins in gray matter are already in the tissue space. For white matter, however, the spins are still virtually all in arteries.